Canadian Grain Commission
17. Corn
Determination of dockage ........................................................................................... 17-2
Definitions ................................................................................................................ 17-2
Dockage not reported .............................................................................................. 17-2
Normal cleaning procedures: .................................................................................. 17-2
Composition of dockage .......................................................................................... 17-3
Estimating test weight of well-matured corn after drying ....................................... 17-4
Grading ......................................................................................................................... 17-5
Important definitions ................................................................................................ 17-5
Net weight of sample ............................................................................ 17-5
Hazardous substances in samples ........................................................ 17-5
Representative portions for grading ........................................................................ 17-5
Grading factors ........................................................................................................ 17-6
Blue-eye mould .................................................................................... 17-6
Caramelized kernels ............................................................................. 17-6
Classes ................................................................................................ 17-6
Contaminated grain .............................................................................. 17-6
Cracked corn and foreign material (CCFM) ........................................... 17-7
Damage (DMG) .................................................................................... 17-7
Earth pellets ......................................................................................... 17-7
Excreta (EXCR) .................................................................................... 17-8
Fertilizer pellets (FERT PLTS) .............................................................. 17-8
Fireburnt (FBNT) .................................................................................. 17-8
Foreign material (FM) ........................................................................... 17-8
Heated (HTD) ....................................................................................... 17-9
Odour (ODOR) ..................................................................................... 17-9
Rotted (ROT) ....................................................................................... 17-9
Stones (STNS) ................................................................................... 17-10
Treated seed and other chemical substances ...................................... 17-12
Varieties ............................................................................................ 17-12
Primary and export grade determinants table ........................................................ 17-13
Corn, Canada Western/Canada Eastern Yellow, White or Mixed (CW/CE) ......... 17-13
Export shipments ....................................................................................................... 17-14
Grading .................................................................................................................. 17-14
Cracked corn and foreign material (CCFM) .......................................................... 17-14
Official Grain Grading Guide
Corn
17-1
August 1, 2016
Canadian Grain Commission
Determination of dockage
Definitions
In Eastern Canada the terms of delivery or terms of a contract will determine if dockage
is to be assessed. In Western Canada dockage may only be assessed on tough, damp,
moist or wet corn. The CGC will only assess dockage upon request. Dockage is assessed
to the nearest 0.1%. Once dockage material has been removed it will not be reintroduced
to the sample to determine the grade.
Cracked Corn and Foreign Material (CCFM) is a grading factor and will be assessed
when determining the grade.
Dockage is defined under the Canada Grain Act as “any material intermixed with a parcel
of grain, other than kernels of grain of a standard of quality fixed by or under this Act for
a grade of that grain that must and can be separated from the parcel of grain before that
grade can be assigned to the grain.” Dockage is removed by following the cleaning
procedures described in this section of the manual.
The sample as it arrives is referred to as the uncleaned or dirty sample. Its weight is the
gross weight of the sample. Dockage is assessed on the gross weight of the sample.
Dockage not reported
▲ Important: Dockage is not reported when corn is graded
• Corn, Sample CE Account Fireburnt
• Corn, Sample Salvage
• Corn, Sample Condemned
Normal cleaning procedures:
▲ Important: Wear gloves and a mask to handle any sample which you suspect may
contain hazardous substances.
Assess dockage before assessing test weight.
Procedures for normal cleaning of corn require
• No. 12 round-hole hand sieve for corn with 25% moisture or less
• No. 14 round-hole hand sieve for corn over 25% moisture
1. Using a Boerner-type divider, divide the uncleaned sample to obtain a representative
portion.
• Official samples shall be at least 1kg.
• Unofficial samples shall be at least 1 kg.
2. Sieve approximately 250 g at a time on the appropriate hand sieve until all possible
material has fallen through the sieve.
3. Handpick material remaining on top of the sieve as described under Composition of
dockage.
Official Grain Grading Guide
Corn
17-2
August 1, 2016
Canadian Grain Commission
Composition of dockage
• All material which passes through the No. 12 or No. 14 round-hole sieve
• All foreign material and pieces of cob handpicked from the sample, excluding stones
Official Grain Grading Guide
Corn
17-3
August 1, 2016
Canadian Grain Commission
Estimating test weight of well-matured corn after drying
Note: Test weight is determined on corn prior to removal of cracked corn and foreign
material. When the Terms of Delivery or terms of a contract state that dockage can be
deducted then test weight is determined after the removal of dockage.
Corn samples that contain a high percentage of moisture typically show an increase in
test weight after drying. Use the following table to predict the test weight of well-matured
corn before drying.
▲ Important: This is only a guide, and works only with well matured corn. Samples
should be checked yearly to ensure that the formula applies for that crop condition.
Amount to add
Moisture range
kg/hl
g/0.5 L
15.8 - 16.4
0.5
2.6
16.5 - 16.9
1.0
5.2
17.0 - 17.3
2.0
10.5
17.4 - 17.6
2.1
11.0
17.7 - 17.9
2.2
11.5
18.0 - 18.3
2.3
12.0
18.4 - 18.6
2.4
12.5
18.7 - 18.9
2.5
13.0
1. Find the moisture range for the test weight of the sample.
2. Add the amount for that moisture range in the appropriate units, either kg/hl or g/l.
▲ Important: Corn samples are not to be downgraded on the basis of an “estimated”
test weight. Questionable samples must be dried by exposure and then have the test
weight determined.
For example,
The moisture for the tested sample is 17.5%, and the test weight is in kg/hl.
Amount to add
Moisture range
kg/hl
g/0.5 L
17.4 - 17.6
2.1
11.0
Add 2.1 to the test weight in kg/hl.
Official Grain Grading Guide
Corn
17-4
August 1, 2016
Canadian Grain Commission
Grading
Important definitions
Net weight of sample
The sample after cleaning and removal of dockage is referred to as the cleaned sample.
Its weight is the net weight of the sample. Percentages by weight for grading refer to
percentages of the net weight.
Hazardous substances in samples
Wear gloves and a mask to handle any samples that you suspect may contain hazardous
substances. Hazardous substances are defined in the Regulations as “any pesticide,
herbicide, desiccant or inoculant.”
Representative portions for grading
All grading is done on representative portions divided down from the cleaned sample,
using a Boerner-type divider.
Values in the following table represent a range of recommended portions of samples for
grading. Refer to definition of “Representative portion” in the glossary for a complete
description of the terms “Minimum”, “Optimum” and “Export”.
Representative portion of corn for grading, grams
Grading factor
Minimum
Optimum
Export
Caramelized kernels
100
500
500
Classes
100
working sample
working sample
working sample
working sample
working sample
Damage
100
500
500
Excreta
working sample
working sample
working sample
Fireburnt
working sample
working sample
working sample
100
500
500
Odour
working sample
working sample
working sample
Stones
500
working sample
working sample
Cracked corn and foreign material
Heated and rotted
Official Grain Grading Guide
Corn
17-5
August 1, 2016
Canadian Grain Commission
Grading factors
Blue-eye mould
Germs of kernels appear dark blue with mould, or there may be just a visible mouldy blue
streak under the hull of the germ. In the second case, peel back the hull from the germ to
examine the germ.
Blue-eye mould is included in the tolerance for Damage.
Representative portion for analysis
Minimum—100 g
Optimum—500 g
Export—500 g
Caramelized kernels
Caramelized kernels are kernels that were very immature when dried at a high
temperature in a dryer, and the heat has turned the kernel to a scorched colour similar to
that of heated kernels. The outer hull of the kernel may be peeled off showing a slightly
damaged kernel inside. These kernels are classed as Damaged.
Representative portion for analysis
Minimum—100 g
Optimum— 500 g
Export— 500 g
Classes
Corn is classed as yellow, white, or mixed. The class forms part of the grade name; for
example, Corn, Sample CW Yellow Account Heated.
Samples of yellow and white corn containing less than 95.0% of one class are designated
Mixed; for example, Corn No. 1 CE Mixed.
Representative portion for analysis
Minimum—100 g
Optimum— working
sample
Export— working
sample
Contaminated grain
▲ Important: Wear gloves and a mask to handle any sample that is suspected of
containing contaminated grain.
Contaminated is defined in the “Canada Grain Act” as; “Contaminated means, in respect
of grain, containing any substance in sufficient quantity that the grain is unfit for
consumption by persons or animals or is adulterated within the meaning of the
regulations made pursuant to sections B.01.046(1), B.15.001 and B.15.002(1) of the Food
and Drugs Act.”
Samples deemed to be contaminated by the Grain Research Laboratory in consultation
with the Chief Grain Inspector for Canada are graded Corn, Sample Condemned.
Official Grain Grading Guide
Corn
17-6
August 1, 2016
Canadian Grain Commission
Cracked corn and foreign material (CCFM)
Cracked corn and foreign material includes any of the following:
• All material including kernels and pieces of kernels of corn or any other grains which
pass through a No. 12 round-hole sieve or, for samples with a moisture level over
25.0%, through the No. 14 round-hole sieve
• All foreign material other than stones handpicked from the sample, including pieces
of cobs that were not removed by sieving
Representative portion for analysis
Minimum—working
Optimum— working
sample
sample
Export— working
sample
Procedures
▲ Important: Follow procedures for assessing dockage.
Note: Because breakage occurs during handling at terminal elevators, round down
percentages by weight of CCFM to the nearest whole number on all officially sampled
and inspected domestic or export shipments from a terminal elevator.
For example, a sample containing 4.7% CCFM by weight is recorded as containing 4.0%
CCFM for grading purposes only on officially sampled and inspected shipments from a
terminal elevator.
Damage (DMG)
Damaged kernels include whole kernels or pieces of kernels which are
• Affected by blue-eye mould and other types of moulds
• Sprouted
• Ground-damaged
• Weathered
• Diseased
• Frosted
• Scorched, from a drier
• Heated, naturally, or from a drier, or caramelized
• Rotted
Representative portion for analysis
Minimum—100 g
Optimum—500 g
Export—500 g
Earth pellets
•
•
Hard earth pellets are pellets that do not crumble under light pressure.
See Stones.
Soft earth pellets are pellets that crumble under light pressure.
See Cracked corn and foreign material.
Official Grain Grading Guide
Corn
17-7
August 1, 2016
Canadian Grain Commission
Excreta (EXCR)
▲ Important: Wear gloves and a mask to handle any samples that you suspect may
contain excreta.
Representative portion for analysis
Minimum—working
Optimum— working
sample
sample
Export— working
sample
Fertilizer pellets (FERT PLTS)
Fertilizer pellets are a manufactured plant nutrient product used by producers in the
production of grain. They are typically small, round or irregular shaped and usually
white, grey, brown, pink or reddish in colour.
Note: Canadian Grain Commission personnel should refer to ISO national work
instruction “Suspect Contaminated Grain, Handling Procedures” for procedures to be
followed when handling samples containing fertilizer pellets.
Representative portion for analysis
Minimum—working
Optimum—working
sample
sample
Export—working
sample
Procedures
• Handpick any fertilizer pellets and determine the concentration basis the net working
sample.
• Fertilizer pellets are assessed as stones when the concentration does not exceed 1.0%
of the net sample weight.
• Samples containing fertilizer pellets in excess of 1.0% of the net sample weight are
graded Corn, Held IP Suspect Contaminated Grain.
Fireburnt (FBNT)
Fireburnt kernels are kernels charred or scorched by fire. A cross-section of a fireburnt
kernel resembles charcoal with numerous air holes. The air holes result in a low weight
kernel which crumbles easily under pressure.
Representative portion for analysis
Minimum—working
Optimum— working
sample
sample
Export— working
sample
Procedures
Samples of corn containing fireburnt kernels are graded Corn, Sample CW/CE (class)
Account /Fireburnt.
Foreign material (FM)
See Cracked corn and foreign material (CCFM).
Official Grain Grading Guide
Corn
17-8
August 1, 2016
Canadian Grain Commission
Heated (HTD)
Heated kernels have at least one of the following characteristics:
• Whole kernels or pieces of kernels which range in colour from amber to dark brown
over the entire kernel
• Kernels which are totally discoloured by fermentation and show no natural colour on
the crowns or dorsals, or both
• The germ of the kernel is amber to dark brown and is severely puffed in the germ
area when heated in a drier
• Heated seeds of other grains are included in the tolerance for Heated
If kernels exhibit none of the above characteristics, but are not whole or sound, they are
classed as Damaged.
Note: Cracked corn and foreign material that is heated is included with heated corn for
grade assessment.
Representative portion for analysis
Minimum—100 g
Optimum—500 g
Export—500 g
Odour (ODOR)
There is no numeric tolerance for odour. Consider
• The basic quality of the sample
• The type and degree of the odour
• The presence of visible residue causing the odour
Grains grading No. 1 through 4 must be cool and sweet. Corn grading No. 5 may have a
slight odour associated with the low quality, but the odour cannot be sour or musty.
Representative portion for analysis
Minimum—working
Optimum— working
sample
sample
If odour is the grade determinant
and there is . . .
Export— working
sample
Then the grade is . . .
An excessive objectionable odour not
associated with the quality of the grain, but not
heated or fireburnt
Corn, Sample CW/CE Account Odour
An excessive heated odour
Corn, Sample CW/CE Account Heated
An excessive fireburnt odour
Corn, Sample CW/CE Account Fireburnt
Rotted (ROT)
Rotted kernels are whole kernels or pieces of kernels which are visibly in advanced
stages of decomposition and feel spongy under pressure. Rotted kernels are included in
the percentage of heated kernels for grade assessment.
Representative portion for analysis
Minimum—100 g
Optimum—500 g
Official Grain Grading Guide
Corn
17-9
Export—500 g
August 1, 2016
Canadian Grain Commission
Stones (STNS)
Stones are hard shale, coal, hard earth pellets, and any other non toxic materials of similar
consistency. Fertilizer pellets are assessed as stones when constituting 1.0% or less of the
net sample weight. (See Fertilizer pellets for specific procedures to be followed when
samples contain fertilizer pellets.)
Representative portion for analysis
Minimum—500 g
Optimum—1000 g
Export—1000 g
Procedures
1. Handpick stones from a representative portion of the cleaned sample.
2. Determine stone concentration in the net sample.
•
•
•
In western Canada samples of grain containing stones in excess of “basic grade”
tolerances, up to 2.5% are graded Corn, Rejected “basic grade” Account Stones. The
“basic grade” refers to a grade established in the Canada Grain Regulations (grades
listed in the first column in grade determinant tables) that would have been assigned
to the sample if it contained no stones.
In eastern Canada samples of grain containing stones in excess of grade tolerances
are degraded to lower grades. Samples containing stones in excess of the tolerance of
the lowest grade established by regulation up to 2.5% are graded Corn, Sample CE
(class) Account Stones.
In western and eastern Canada grain containing more than 2.5% stones is graded
Corn, Sample Salvage.
Official Grain Grading Guide
Corn
17-10
August 1, 2016
Canadian Grain Commission
Examples: Western Canada
Excerpt from grade determinant tables for
Corn, Canada Western, White, Yellow or Mixed
Grade name
Stones
%
No. 1 CW
0.15
No. 2 CW
0.15
No. 3 CW
0.15
No. 4 CW
0.15
No. 5 CW
0.15
Basic grade:......................... Corn, No. 2 CW Yellow
Reason for basic grade: ....... 3.0% Cracked corn and foreign material
If the above sample
contained
Grade in Western Canada
0.5% stones
Corn, Rejected No. 2 CW Yellow Account Stones
3.0% stones
Corn, Sample Salvage
Examples: Eastern Canada
Excerpt from grade determinants table for
Corn, Canada Eastern, White, Yellow or Mixed
Grade name
Stones
%
No. 1 CE
0.15
No. 2 CE
0.15
No. 3 CE
0.15
No. 4 CE
0.15
No. 5 CE
0.15
Basic grade:......................... Corn, No. 2 CE Yellow
Reason for basic grade: ....... 3.0% Cracked corn and foreign material
Official Grain Grading Guide
Corn
If the above sample
contained
Grade in Eastern Canada
0.5% stones
Corn, Sample CE Yellow Account Stones
3.0% stones
Corn, Sample Salvage
17-11
August 1, 2016
Canadian Grain Commission
Treated seed and other chemical substances
Treated seed
Treated seed is grain that has been coated with an agricultural chemical for agronomic
purposes. These seed dressings contain a dye to render the treated seed visually
conspicuous. The colour of the dye varies depending upon the type of treatment and the
type of grain. The current Canadian colour standards for pesticide seed treatments are:
cereals–pink or red, canola–baby blue or green. Seed treated with an inoculant may have
a green stain. The coatings or stains may appear greasy or powdery and surface area
distribution ranges from tiny flecks to complete coverage.
Other chemical substances
Other chemical substances refers to any chemical residues either adhering to the kernel or
remaining in the sample and to samples having a chemical odour of any kind.
▲ Important: Wear gloves and a mask to handle any samples that you suspect may
contain contaminated grain.
Representative portion for analysis
Minimum—working
Optimum—working
sample
sample
Export—working
sample
If a sample is suspected of being coated with a pesticide, desiccant, inoculant or if the
sample contains evidence of any foreign chemical substance other than fertilizer pellets,
the sample shall be graded Corn, Held IP Suspect Contaminated Grain.
Note: Canadian Grain Commission personnel should refer to ISO national work
instruction “Suspect Contaminated Grain, Handling Procedures” for specific procedures
to be followed when handling samples suspected of containing treated seed or other
chemical substances.
Varieties
Corn is graded without reference to variety.
Official Grain Grading Guide
Corn
17-12
August 1, 2016
Canadian Grain Commission
Primary and export grade determinants table
Corn, Canada Western/Canada Eastern Yellow, White or Mixed (CW/CE)
Standard of quality
Grade name
Minimum test weight
kg/hL
(g/0.5 L)
Degree of
soundness
Damage
Foreign material
Heated
%
Total
%
Stones
%
Excreta
%
Total Cracked corn and
foreign material
%
Other classes
%
No. 1 CW/CE
68
(343)
Cool and sweet,
uniform size
0.1
3
0.15
0.02
2
5
No. 2 CW/CE
66
(333)
Cool and sweet
0.2
5
0.15
0.02
3
5
No. 3 CW/CE
64
(322)
Cool and sweet
0.5
7
0.15
0.02
5
5
No. 4 CW/CE
62
(311)
Cool and sweet
1
10
0.15
0.02
7
5
No. 5 CW/CE
58
(291)
May have a slight
odour, not sour or
musty
3
15
0.15
0.02
12
5
Grade, if No. 5
specs not met
Corn, Sample CW/CE
(class) Account Light
Weight
Corn, Sample
CW/CE (class)
Account Heated
Corn, Sample
CW/CE (class)
Account Damaged
2.5% or less—Corn,
Corn, Sample CW/CE
Rejected (grade) (class) (class) Account
Account Stones or Corn, Excreta
Sample CE (class)
Account Stones
Over 2.5%—Corn,
Sample Salvage
50% or less – Corn
Sample CW/CE (class)
Account CCFM
Over 50% - sample
Cracked Corn and Foreign
Material
Over 5%—Use all
other grading criteria
and grade as Corn
(grade) Mixed
Note: The colour is added to the grade name.
Official Grain Grading Guide
Corn
17-13
August 1, 2016
Canadian Grain Commission
Export shipments
Grading
Corn on export is graded in accordance with primary grade standards and specifications.
Cracked corn and foreign material (CCFM)
Because breakage occurs during handling at terminal elevators, round down percentages
by weight of CCFM to the nearest whole number on all officially sampled and inspected
domestic or export shipments from a terminal elevator.
For example, a sample containing 4.7% CCFM by weight is recorded as containing 4.0%
CCFM for grading purposes only on officially sampled and inspected shipments from a
terminal elevator.
Official Grain Grading Guide
Corn
17-14
August 1, 2016